// JSON数据源
// http://api.douban.com/v2/movie/top250
// JSON数据格式化
// http://tool.oschina.net/codeformat/json

//获取异步访问对象
var xmlhttp;
if(window.XMLHttpRequest){
//IE7+, FireFox, Chrome, Opera, Safari
     xmlhttp = new XMLHttpRequest();
    }else{
    //IE6
    xmlhttp = new ActiveXObject("Micosoft.XMLHTTP");
    }

    var news_content = document.getElementById("news_content");

    //HTTP是无状态，定义一些状态值描述当前HTTP的性质
    //404(not found) 200(ok)  50x(服务器应用程序错误)
    //定义回调函数
    xmlhttp.onreadystatechange = function(){
    if(xmlhttp.readyState === 4 && xmlhttp.status === 200){
                  //news_content.innerHTML = xmlhttp.responseText;
                      //JSON.parse()把文本数据解析为Json对象
                          showJson(JSON.parse(xmlhttp.responseText));
              }
    }

    //HTTP访问方法：GET   POST  ...
    // xmlhttp.open("GET", "http://api.douban.com/v2/movie/top250", true);
    xmlhttp.open("GET", "top250.json", true);
    xmlhttp.send();

    function showJson(jsonData) {
    document.getElementById("title").innerText = jsonData.title;
    var tempHtml = "";
    for (var i = 0; i < 10; i++) {
    // tempHtml += "<li>" + jsonData.subjects[i].title + "</li>\n";
    tempHtml += "<li>";
    tempHtml += jsonData.subjects[i].title;
    tempHtml += "<img src=\"";
    tempHtml += jsonData.subjects[i].images.medium;
    tempHtml += "\" alt=\"";
    tempHtml += jsonData.subjects[i].title;
    tempHtml += "\">";
    tempHtml += "</li>";
    }

    document.getElementById("news_list").innerHTML = tempHtml;
    }